PLGAs are generally obtained by ring-opening (co)polymerization of lactide and glycolide. These monomers derived from lactic acid and glycolic acid are the prototypes of 2,5-dioxane-1,4-diones. Modification of the properties of the PLGAs is of great importance, in particular in their use as a biodegradable and bioassimilable matrix for the trapping and controlled release of active ingredients. Somewhat surprisingly, the approach which consists of modifying the substituents of the 2,5-dioxane-1,4-dione backbone has only been slightly developed up to the present, which can in practice be explained by the somewhat low accessibility of these units.

Symmetrical monomers such a lactide or glycolide are generally prepared from the corresponding α-hydroxy acids. This approach is difficult as it requires the elimination of the water formed and the distillation under vacuum of the monomer. In order to access asymmetrical monomers, two different precursors must be used, typically an α-hydroxy acid and a mono- or di-halogenated derivative (C.-M. Dong et al., J. Polym. Sci. Part A: Polym. Chem. 2000, 38, 4179-4184; M. Leemhuis et al., Eur. J. Org. Chem. 2003, 3344-3349).

In practice, the major limitation of all these synthesis strategies is probably the final stage of closing the ring with 6 members which is inherently in competition with the formation of dimers and oligomers, by intermolecular rather than intramolecular route. The applicant has therefore envisaged a novel synthesis route for 2,5-dioxane-1,4-diones.